I. Field of the Invention
The present invention relates to a microorganism culturing device and, more particularly, to such a culturing device in which the inner atmosphere is maintained in a hermetically sealed state prior to culturing the microorganisms, and generated gases can be discharged, while maintaining the culturing conditions during the culturing process. It also relates to a method for culturing microorganisms using such a device.
II. Description of the Prior Art
Heretofore, the culture of anaerobic microorganisms has been carried out in culturing vessels completely sealed with elastic stoppers such as rubber stoppers, screw caps, seamers or the like.
In the culture of anaerobic microorganisms, however, when a collecting needle penetrates the stopper element for transplantation after incubation, the culture medium tends to spout through the needle due to the inner pressure. Further, the stoppers such as screw caps, seamers or the like tend to be blown off when they are being removed so that operators are often exposed to danger. Furthermore, when such incidents occur, outside air comes into contact with the culture medium so that bacteria in the air contaminate the medium.
Where stoppers with simple fastener members are used, the stoppers may often be blown off during incubation due to increased inner pressure in the culturing vessel produced by gases generated by the anaerobic microorganisms, whereby the culture medium becomes contaminated by bacteria in the open air.
Furthermore, the surrounding areas may become contaminated if the anaerobic organisms are scattered about when the stoppers blow off.
In the culture of aerobic microorganisms, on the other hand, the culturing vessels have been closed with stoppers which are permeable to air such as Morton caps, cotton plugs, aluminum caps, paper ball stoppers or the like. The culture of aerobic microorganisms, however, has several disadvantages: the culture medium cannot be stored for any length of time due to the air-permeability of the stopper of the culturing vessel; bacteria in the open air readily contaminate the medium by entering the open end of the vessel when the stopper is taken out for collection of the culture medium; there is difficulty in transporting culturing vessels with culture media due to leakage; and operators are exposed to danger as a result of this leakage.
In conventional culture methods, it is necessary to take out the stoppers when collecting samples. This, however, allows bacteria in the open air to invade the culturing vessel, so that the bacteria are incubated together with the culture organisms. This sometimes causes difficulty in distinguishing the culture organisms from the contaminating bacteria.
The culture of any of aerobic and anaerobic microorganisms in the same culturing vessels or devices has caused problems in that, when the airtight stoppers as mentioned hereinabove were used, the propagation of the aerobic microorganisms was hindered and, when the air-permeable stoppers were employed, the propagation of the anaerobic organisms was hindered. Accordingly, it has been necessary to utilize a separate culturing vessel or device for culturing aerobic and anaerobic microorganisms, respectively. This has increased the labor involved in culture procedures and made it difficult or impossible to carry out the culture in a rational, safe and sure way.